A June 9 statement by the United States Geological Survey (USGS) said affected birds had "eye swelling and crusty discharge." Birds hit with the disease also exhibited "wobbly movements" that suggested neurological impairment. The disease appeared to be affecting fledgling grackles and blue jays, two bird species commonly found in the mid-Atlantic region.
Virginia Department of Wildlife Resources veterinarian Megan Kirchgessner said: "[The disease] seems to be pretty widespread, and also it's extending for a pretty good period of time." She added that the disease "is continuing" as of writing. Environmental agencies in the four states, alongside the USGS and the National Park Service, have conducted an investigation on the mysterious disease.
The USGS statement noted that birds gathering at bird baths and feeders can transmit the disease to each other. Thus, it asked people to remove the baths and feeders until the end of the outbreak. It also called on people to clean both feeders and baths with a 10 percent bleach solution as an added precaution.
"In the springtime when food is abundant, there's no reason for those feeders to be out. And to be perfectly honest, especially in a situation like this, they can do more harm than good," Kirchgessner said.
The USGS advised against handling birds, especially sick or dead ones. If dead birds ought to be removed, it prescribed wearing disposable gloves and putting the bird carcasses inside sealable plastic bags before putting them inside trash bins. The service also added that pets must be kept away from sick or dead birds.
The strange epidemic in the mid-Atlantic region followed an earlier mass death of birds in the southwestern U.S. Back in September 2020, an "unprecedented amount" of migratory songbirds dying out was reported in the state of New Mexico.
Initially, hundreds of dead birds first turned up at the U.S. Army White Sands Missile Range and White Sands National Monument. The entirety of New Mexico subsequently reported many bird carcasses turning up everywhere. Other states such as Colorado and Texas also reported dead bird species such as warblers, bluebirds, sparrows and blackbirds. (Related: Unprecedented number of birds dead in New Mexico in a mysterious die-off.)
Researchers and biologists in the southwest have also noted the birds acting strangely before they died. The birds were lethargic and unresponsive, which led to them frequently colliding with vehicles.
They analyzed some of the dead birds and 80 percent of the samples they examined showed signs of "severe emaciation." These included empty stomachs, a lack of fat deposits and severely shrunken breast muscle. However, laboratory results ruled out any pathogens, parasites or chemicals as the cause of the mass bird deaths.
Thus, researchers narrowed down the possible cause of the bird deaths to climate change. They posited that wildfires that ravaged California and other western states last year either forced the birds to migrate sooner or take longer routes that depleted their energy reserves. Biologists with the New Mexico Department of Game and Fish added that a surprise cold snap in early September 2020 contributed to the number of avian fatalities.
New Mexico State University biologist Martha Desmond said: "It's very difficult to put a finger on exactly what [the] number of [dead birds are], but I can say it would easily be in the hundreds of thousands of birds."
She and other researchers noted that majority of the birds that died ate insects and seeds as their food. Desmond added: "A number of these species are already in trouble. They are already experiencing huge population declines – and then to have a traumatic event likes this is … devastating."
In an October 2019 report, the National Audubon Society (NAS) noted that two-thirds of North American birds – equivalent to 389 species – risk extinction due to climate change. NAS President and CEO David Yarnold said: "Two-thirds of America's birds are threatened with extinction from climate change, but keeping global temperatures down will help up to 76 percent of them."
NAS Senior Climate Scientist Brooke Bateman emphasized the importance of the group's findings in the report. "Birds are [an] important indicator species because if an ecosystem is broken for birds, it is or soon will be for people too," she said. (Related: Bird populations in America and Canada have declined by 29 percent, warn researchers.)
Ecology.news has more stories about mysterious bird deaths in different parts of the country.